Find & add a version bump system that can handle app & python versions

[hwine]

Besides the version of frost itself, there are other version numbers that need to be updated in several places. One example will be the Python version number, which appears in various files such as Dockerfile, tox.ini, .pre-commit-config.yaml (#419).

Having so many places to change to upgrade leads to an error prone manual process.

There are tools, such as bump2version which handle application versioning well. We may need to search for a tool that can handle 2 sets of version numbers. (They also provide a list of alternatives.)